Telescoping stackers are used to pick up a load and to convey it to another place with the aid of the complex wheel-type chassis. On the other hand, these rigs work more or less in a stationary manner when the considerable reach and height of their telescoping arm is utilised, for example, to convey some material to be loaded to a construction site to a height of 10 meters and to set it down there at an exactly determined place. In these cases, the rig must be stabilised and, on uneven ground, be horizontalised laterally to the vehicle's longitudinal axis so that the steeply adjustable telescopic mast, including its load, remains roughly in the perpendicular plane enclosing the vehicle's longitudinal axis. Although a person operating the rig quickly develops practice in travelling precisely to the loading or unloading target and in performing the required stabilisation, there remains the more difficult task of moving a load laterally by about 0.5 m at the substantial distance given when the telescopic mast is extended in order, for example, to travel it into a laterally restricted aperture in a building.
To perform this transverse motion of the load, it is known to provide as the fork carrier a hydraulically activated transverse slide whose rails are affixed to the telescopic mast end. Due to the weight of transverse slides, rails and drive means, however, the working load is reduced, which makes itself felt disadvantageously in a restrictive manner above all with telescope lifts of up to 10 meters.
To swivel a heavy load transporting vehicle laterally in place under confined conditions without moving backwards or forwards, a stabilising device which can be lowered from the end of the vehicle frame is known from DE 23 60 825 C2, which stabilising device possesses fixed perpendicular hydraulic jacks on the vehicle frame and a beam resting on the travel formation and curved in accordance with the intended swivel radius. As the top section of the beam divided in the longitudinal direction, which top section is connected rigidly to the hydraulic jacks, is supported movably on the lower section and as both beam sections can be moved relatively to each other by a motor, the vehicle can be swivelled laterally in an angle roughly given by the beam length at its end raised by the stabilising device.
From U.S. Pat. No. 4,923,361 a device for sidewards motion for a fork-lift is known whose vehicle frame is stabilised by means of a rear steering wheel pair and by means of two front wheels supported on rigid-mounted axles. On the bottom side of two fork tines extending forwards to over the front wheels there are disposed supporting legs swivellable around axes running in the direction of the tines whose free end supports a base supported in an articulated manner. With a raised stacker fork, in order to effect a sidewards motion, a supporting leg is pivoted down from each fork tine by pedal actuation into a final position determined by a stop in which final position its direction of extension forms an acute angle with the perpendicular. If due to a motorised lowering of the stacker fork the slanted supporting legs come into contact with the floor with their bases, the front wheels thus relieved in part lose their floor contact and perform a limited sidewards motion together with the front end of the vehicle frame until, as the slant of the supporting legs moving in the direction of their horizontal position of rest in the folded-up position increases, the friction connection of the bases with the floor ends. To perform sidewards motions in opposite directions, there are disposed on both fork tines two supporting legs each which can be slanted in opposite directions of which depending on the intended motion direction one supporting leg is folded down by pedal actuation.
On this basis, the object of the invention is to provide a mobile rig on wheels with transverse motion of the type given above with a simplified device for the transverse motion of the rig.